Electromagnetic flowmeters are commonly used in various industries to measure the flow rate of conductive fluids flowing through pipelines or other conduits. In principle, electromagnetic flowmeters generate a magnetic field in a conduit for flow of fluid through the meter. When conductive fluid flows through the conduit, the magnetic field induces a voltage difference between two locations in the fluid that are spaced apart in a direction transverse to the fluid flow. The magnitude of the voltage difference is related to flow rate. By detecting the voltage difference, fluid flow rate can be measured. The voltage is calibrated to the fluid velocity. The fluid velocity can be used in combination with the cross sectional flow area to obtain a volumetric flow rate measurement. If the density of the fluid is known, the volumetric flow rate can be converted to a mass flow rate.
In some applications, calibration of an electromagnetic meter must be verified on an ongoing basis. Components of an electromagnetic meter may degrade over time. For instance, insulation between the turns of the coils used to generate the magnetic field may degrade and cause shorted turns. Also, magnetic components may shift due to vibrations or for other reasons. These problems and others that may arise over time during use of an electromagnetic flowmeter can affect accuracy of the flow rate measurement. Verification of the meter provides assurance that the meter is still working in good order. Conversely, a meter verification system can identify when an electromagnetic meter is not working properly so that the meter can be taken offline and replaced or repaired.
Some conventional electromagnetic meters include meter verification systems. However, the present inventor has made certain improvements, which will be described in detail below.